Figure 2.

(a) Ribbon diagram of the LdPTR1 tetramer. Subunits A and B constitute the asymmetric unit. (b) Ribbon diagram of an LdPTR1 subunit. Seven red β-strands (numbered) are sandwiched between the blue α-helices; loop regions are coloured yellow. A sulfate is depicted as sticks in the active site with S coloured orange and O red; the N- and C-termini of the protein are labelled. Blue, red and black asterisks mark residues either side of the missing β3–α3, β4–α4 and β6–α6 loops, respectively.